A 4×12 ft concrete slab at 4" thick requires roughly 0.59 yd³ of concrete — or 0.65 yd³ with a standard 10% waste factor. That works out to approximately 30 × 80 lb bags (or 40 × 60 lb bags) for bagged concrete. Common for patios, walkways, and small pads. Use the calculator below to adjust thickness, waste, and pricing.
Slab Dimensions
Common thickness:
Slab Preview
Diagram is illustrative — not to scale
Waste & Options
Price Per Unit (optional)
Prices vary by region. Adjust to match your local supplier.
Measuring an irregular patio or curved walkway? Stop guessing the square footage. Open our AI app, point your camera at the excavated area, and let the AI calculate the exact volume and material list instantly.
Volume
Material Needed
Less than 1 full truck — consider using bags (trucks typically carry 8–10 yd³)
Estimated Cost
80 lb bags
$225.00
60 lb bags
$220.00
Ready-mix
$114.07
Cost estimates are approximate. Adjust prices in the panel on the left.
Curved walkways, L-shaped patios, and odd-dimension slabs are impossible to calculate by hand. Point your camera at the area — Suparate reads the geometry and gives you the exact material list.
Need a different size? Use the full hub with all options.
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